China criticised US officials for "immoral and irresponsible" comments that blamed Beijing's response to the coronavirus for worsening the global impact of the pandemic.
On Wednesday, US national security advisor Robert O'Brien accused China of a slow response to the initial emergence of the coronavirus, saying this had probably cost the world two months when it could have been preparing for the outbreak.
Asked about O'Brien's comments, China's Foreign Ministry spokesman Geng Shuang told a news conference in Beijing on Thursday that "immoral and irresponsible" remarks by certain officials would not help US epidemic efforts.
China's efforts to slow the spread had bought the world time to prepare against the epidemic, said Geng Shuang.
"We wish that a few officials in the US would at this time concentrate their energy on responding to the virus and promoting cooperation, and not on shifting the blame to China."
The coronavirus emerged in December in the central Chinese city of Wuhan and surrounding Hubei province, where around two thirds of global cases so far have been recorded. But in recent weeks the vast majority of new cases have been outside China.
The Chinese authorities credit firm measures they took in January and February, including to a near total shutdown of Hubei, for preventing outbreaks in other Chinese cities on the scale of Wuhan and slowing the spread abroad.
The administration of US President Donald Trump has pointed to a decision to limit air travel from China at the end of January to fend off criticism that it responded too slowly to the disease. Critics say Trump played down the disease in public and the federal government was slow to roll out tests.
"Unfortunately, rather than using best practices, this outbreak in Wuhan was covered up," Trump's national security advisor O'Brien said during a think-tank appearance on Wednesday.
"It probably cost the world community two months to respond," during which "we could have dramatically curtailed what happened both in China and what's now happening across the world," he said.
More than 119,100 people have been infected by the novel coronavirus across the world and 4,298 have died, the vast majority in China, according to a Reuters tally. The United States has 975 cases and 30 people have died.
"We have done a good job responding to it but ... the way that this started out in China, and the way it was handled from the outset, was not right," said O'Brien.